Protractor



Patented Apr. 13, 1943 simsa- ENT j orluclz' A PROTRACTOR .Timothy A. Schaefer, west Anis, wis., assigner .to Industrial `Engineering Co. Inc., Minneapolia a corporation of Minnesota l .Application February 16, 1942, Serial No. 431,018

3 Claims.

My invention relates to improvements in protractors and, more particularly,.to a protractor of the pocket type.

The improved protractor, while intended for general use, is, due to its novel construction and` .ment, and it is also capable of taking certain measurements which are difficult to obtain and cannot now be taken with presentinstrum'ents. Another object of the invention is to provide a 4protractor that is of light weight, thin and having rno projecting set-screws or i other `clamping devices, thus well adapting the carried ink a pocket.

`protractor to `be fStill anotherobject ofthe invention is to provide `a protractor for measuring, with greater accuracy than is usuallyrequired, angles under `all conditions including those difcult to get at and for measuring angles in shallow blindholes and similar instances. i

Another object of this invention is to provide 'a protractor that can also be used as a depth gauge.A i

Other objects will be apparent fromthe-fol- 'lowing description, reference being had to the accompanying drawing. .f

To the above end, generally stated, the'invention consists of the novel devices and combinations of devices hereinafter described and dened in theV claims.

In the accompanying drawing, which illu'strates the invention, like characters indicate like parts throughout the several views.

Referring to the drawing: 1

Fig. 1 is `a plan View of the improved protractor, a part thereof being broken away and sectioned; Y .1 1

Fig. 2 is a front elevation of the same;

. Fig.` 3 is a fragmentary detail view principally `in section taken on the line 3-3 of Fig. 1,'on1an 4enlarged scale; z.

Figs. 4, 5 and Gare perspective views, on an enlarged scale, of the body member, pivot mem- 4berand 'lock washer removed fromthe protraci't'or'and 'Ito-1l', inclusive, are views of the im- `tric with said circle.

proved protractor, in diagram on a reduced scale', applied to different objects, certain of which are in section, to illustrate diiferent difficult angles that'can bemeasured to determine the angles thereof in degrees and fractions thereof.

The numeral I2 indicates abase in the form of a thin metal plate having a long supporting straight edge or surface I3 and a short supponting straight edge or surface I4. These two supporting edges I3 and I4 are at right angles to each other and the former is at the left-hand end of said base with reference to Fig. 1. The righthand end portion of the base I 2` is materially reduced in width to aiord a relatively long narrow blade I5, the upper edge of which is designated b-y the numeral I6 and is parallel to the supporting edge I3.

A pivot Il is mounted onthe base I2 between the supporting edge I4 and the inner end ofthe blade I5 and substantially midway between the supporting edge I3 and the overlying upperA edge of'said base. This. pivot I1 is inserted through a transverse hole in the base I2, from the back thereof and is rigidly secured to said base by a pressed t or otherwise. A large `head I8 on the pivot I'I engages the back of the base I2 and holds said pivot with its longitudinal axis perpendicular to the face of the base I2. The pivot Il has an axial bore I9, is internally screwthreaded and outwardly of said base is reduced somewhat in diameter. A pair of diametrically opposite keyways 20 are formed in the free -or outer end portion of the pivot I1. x

The base I2 has a scale 2| of inches and frac'- tions thereof marked on its face, at the supporting edge I3, and reads from theiright to the left. A circle 22 having its center at the axis of the pivot I1 is divided intoa scale 23 of three hundred sixty degrees (360) and the zero point in said scale is at the top of the base I2 on a radial line extending from the axis .of the pivot I1 parallel to the supporting edge I4.` The degrees in the circle 22 are numbered in tens, reading from one (l) to one hundred eighty degrees (180) in opposite directions from zero. The upper edge portion of the base I2, from zero on the scale 23 to substantially the blade I5, is concen- A body member 24 in the form vof a flat metal plate is mounted at its center on the pivot for rotation thereon. This body member 24 has a beveled edge 25 on the arc of a circle that is concentric with the circle 22 and closely Yengages the degree marks of the scale 25 at their inner ends. A-position mark 26 on the beveled edge 25 is provided to indicate where the reading on the scale 23 is to be taken and extends on a radial line from the axis of the pivot I1.

Formed in the body member 24 is a passageway 21 that is diametrically opposite the position mark 26 and extends at right angles to a radial line extending from said mark through the axis of the pivot I1 to the passageway 21. This pas,- sageway 21 is rectangular in cross-section and a relatively narrow slot 28 in the back of the head 24 extends into said passageway, see Fig. 4.

A large thin waxed washer 29 on the pivot I1 is interposed between the face of the base I2 and the back of the body member 24. rFormed rin the top of the body member 24 is an annular depression 3l) that surrounds the pivot I1 and is conlcentric therewith. A relatively thin washer 3|, that is loose on the pivot I1, rests on the Ibody member 24 at the bottom of the depression 30. Resting on the washer 3| is a relatively thick washer 132 having a pair of Vdiametrically .opposite keys 133 that extend into the keyways 2i) and lock the washer 32 to the .pivot I1. A screw stud 34 extends-into the bore I9 and has threaded engagement with the internal screw threads on the pivot I1, and which pivot acts as a fixed nut for the stud 34. An annular face plate 35, rigidly secured .to the screw stud 34 at its outer end, rests on .the washer 32 and has a radially projecting finger-piece 36 by which said stud may be turned in the pivot I1.

,Obviously the base `I2 and the face plate 35 aord clamping members which may be actuated by the screw stud `34 and the cri-operating nut- -acting pivot I1 to frictionally clamp the washer 29, the body member 24, the washer 3| and the washer 32' between said base and face plate,

Aflong narrow metal arm 31 is mounted in the passagewayl 21 for endwise sliding movement and for removal -irom said passageway to be turned end for end and again inserted in the passageway y21. This arm 31 has a scale 33 of inches and frictions thereof marked thereon and one end of said arm is square and the other end thereof is beveled on van angle of forty-ve degrees (45).

.'Gbviously, when the position mark 2i is ,on aero of the scale 23, the arm 3.1 is parallel to the supporting edge I3 of the base I2. The arm 3'! Ais frictionally heldin the body member 2.4 by a spring member 39 having at its ends outturned vears Mi that engage opposite sides of the vbody member 24 and thereby hold said member againstI endwise movement in the passageway 21. The 4tension ofthe spring member 39 is sufficient to securely hold the arm* 31 against accidental endwise movement wherever positioned in the body member 24.

From the above description, it is evident vthat the narrow arm 3l' makes it possible to take measurements in .difficult or vrestricted places. The thinness of the protractor is very important as vit permits the arm 31 to lie close to an object being measured, see Fig. 7. By mounting .the arm A31 in the body member 24 for endwise adjustment, it is possible to take measurements, as shown vin Figs..7 to 1 1, inclusive. The waxed washer 29 maintains the proper friction between the base I2' and the head member 24 .and holds the relative position of the head member 24 to the base I2 at which it was set. The purpose of keying the washer 32 to the screw stud 34 is to prevent said washer from turning the face plate 35 when Vthe head member '12.4 is moved about y,its axis and thereby turn said stud and change the fictional contact of the members clamped between the base I2 of the face plate 35. It is evident that the screw stud 34 may be adjusted to positively lock the head member 24 from turning, or it can be adjusted so that said head member may be turned but will remain where positioned. By reversing the arm 31 end for end, from its position shown in Fig. 1, the beveled end of said arm may be used when measuring angles, as shown in Figs. 7 to 11, inclusive.

The protractor may be used as a depth gauge by resting the base I2 at either of its supporting edges I3 or I4 on the object being measured and taking the reading on the scale 38 at the respective supporting edge.

` When Vthe protractor is not in use, the head 4member 24 maybe adjusted to bring the arm 31 into a position in which it is parallel to the base I2 and said arm .endwise adjusted to position its ends at the ends of said base. With the protractor thus adjusted,`the same occupies very little Espa-Ce and vmay be easily carried ,in a pocket.

During the use of the improved protractor, all adjustments thereof are accomplished without the use of `set-screws or other clamping devices. fIn .ease it is desirable lto positively hold the head `member 24 from turning, it is -only neceSSary yto move the ngerpiece l36.

From what has been said, it will be understood vthat-the p rotractor described is capable of modifications as to details of construction and arrangement wgithin the scopek of the invention herein disclosed Vand claimed.

' What I claim is;

` 1. In a protractor, a thin base having a straight edge, an lupstanding internally screw-threaded tubular pivot rigidly secured to the base, a hat y'body member turnably mounted on the pivot, a screw stud inthe pivot, ay face plate rigidly secured to the screw stud and overlying the body member, said faceplate being operable to turn the screw stud Ain the pivot and said screw inturn llmove the face plate relative to the -base andinotionally clamp the body member therebetween, and a thin narrow arm mounted kon the :body member vfor endw-ise adjustment, said base having a scale of degrees'therleon and said body member havling ,a vposition mark cooperating with `said sca e.

2. In a protraotor, a thin ibase having two straight edges that extend at'right angles theone to the other, -an internally screw-threaded pivot rigidly secured to the base, a hat body member turnably mounted on the pivot, a thin washer loose on the pivot between the base and the :body

member, a thin washer vloose on the `pivot and resting .on the body member, a relatively thick .Washer on the pivot, resting on the last noted 4thin washer and said screw in turn heldiby thepivot against rotation but free for axial movement thereon and extending outwardly of the outer end of the pivot, a screwstudin the pivot, aiace plate rigidly secured to the screw stud and resting on said thick washer, saidfface ,plate I,being operable .to turn-the screw stud in the .pivot and-movethe face plate relative to the base and vfrictionally clamp the body member and the washers therebetween, and a thin narrow arm mounted on the -body member 'for endwise adjustment, said base turnably mounted on the pivot, a thin lower washer loose on the pvot between the base and body member, a thin upper washer loose on the pivot and resting on the body member, a relatively thick washer on the pivot, resting on the thin lower washer and extending outwardly of the outer end of the pivot, said pivot having a keyway and said relatively thick Washer having a key extending into the keyway and holding said Washer against rotation on the screw stud but with freedom for relative axial movement, a screw stud in the pivot, a face plate rigidly secured to the screw stud, resting on said thick washer and having a radially projecting ngerpiece by which vsaid face plate may be rotated to turn the screw to its axis, a thin narrow arm mounted on the passageway for endwise adjustment, and spring means frictionally holding the arm relative to the body member, said base having a scale of degrees thereon, and said body member having a position mark thereon cooperating with said scale, said mark being diametrically opposite the passageway and on a line perpendicular to the arm and extending through the axis of the pivot.

TIMOTHY A. SCHAEFER. 

